The use of genetically engineered dengue proteins represents a promising vaccine strategy. We have employed the high yielding baculovirus-insect cell system to achieve expression of dengue viral proteins from cloned DNA sequences. A recombinant baculovirus containing a 4.0 kilo-base dengue virus cDNA sequence that codes for the three viral structural proteins, capsid (c) protein, premembrane (PreM) protein, and envelope glycoprotein (E), and nonstructural proteins NS1 and NS2a. Cultured insect cells infected with this recombinant virus produced what appeared to be authentic E and NS1. Immunization of mice with these dengue protein products induced resistance to fatal dengue encephalitis. To further elucidate the basis for this protective immunity, recombinant baculovirus that expressed only E or NS1 was constructed. Mice immunized with an infected cell lysate containing either E or NS1 also developed complete resistance to dengue virus challenge.